It's crunch time for President Obama and the congressional Democrats. The political stakes are clear. If they want to ensure that they will be slaughtered in the November congressional elections, all they need to do, in the weeks ahead, is screw up their golden opportunity to pass health care reform.

Being Democrats, they are entirely capable of screwing this up. But if that happens, they will create the optimal conditions for losing their majorities - much the way they were decimated back in November '94, when the failure to enact Clinton-sponsored health care reform prompted millions of disappointed Democrats to stay home on election day.

The current conventional wisdom decrees that the Democrats will lose scores of seats in November if they do pass health reform; according to polls, swing-voting independents generally oppose the sweep and price tag of Obama's proposed overhaul. But midterm elections are typically dominated by the most partisan voters. If the left is more enthused and motivated than the right, Democrats tend to win. If the right is more stoked than the left, Republicans tend to win. Eight months before election day, the right is clearly more ginned up for the balloting; anger is a great motivator.

Democrats are poised to lose a lot of seats this year, for cyclical reasons alone. Alan Abramowitz, an Emory University political analyst with a long track record of forecasting congressional elections, wrote the other day: "The main reasons that Democrats are likely to experience significant losses in 2010 are the normal tendency of voters to turn against the president's party in midterm elections, regardless of the national political environment; and the fact that, after gaining more than 50 seats in the past two elections, (Democrats) are defending a large number of seats, many in Republican-leaning districts."

So, basically, Democrats can't even hope to minimize their November losses unless they give their own partisans a darn good reason to show up. So far, there is no such reason. As the well-caffeinated James Carville said on ABC the other day, "When you're a governing party, and you have a majority like we do, and we have the presidency, then sometimes you have to step up and do something."

Obama won a decisive '08 victory (in part by campaigning for health reform), the Democrats have huge margins in both congressional chambers, yet they've barely done squat to move the Democratic agenda (thanks to the Senate). Failing now on health reform - when they have the votes for passage and the parliamentary route for passage - would likely put the kibosh on Democratic turnout. Liberal voters, black voters, and particularly the young voters who backed Obama so enthusiastically, are likely to ask themselves, "If these people can't get anything done, even with their big majorities, then why should I bother to vote?"

Politically speaking, Democratic lawmakers basically have two choices: They can pass health reform this spring, and spend the rest of the campaign year touting all the historic good stuff; or they can do nothing, and spend the rest of the year defending that. In other words, they can choose to be proactive and upbeat, or they can choose to be timid and downbeat.

The latter is no way to win. Yet that's the route Democrats took in 1994. After they whiffed on Clinton health reform (which never even came to a floor vote), Democratic partisans basically concluded that their representatives in Washington couldn't govern. So they stayed home, ceding the electoral battlefield to the opposition.

Republican turnout, when measured against the previous midterms of 1990, was higher in every region of the country; Democratic turnout was down everywhere except in the Middle Atlantic and far West states - with precipitous falloffs among low-income voters, minority voters, and young voters. All told, one turnout expert concluded in a report that the '94 midterm "was more of a negative mandate against the Democrats rather than a positive mandate for the Republicans."

Democrats today potentially face the same negative mandate; not only is the Democratic base disillusioned by the stasis on health reform, but polls specifically pinpoint a waning of enthusiasm among the young. The nonpartisan Pew Research Center reports that voters aged 18 to 29 - Obama's strongest '08 cohort, and the age bracket that is most supportive of government activism - have "cooled" considerably in their views of Obama and the Democrats. If Democrats want to hasten that cooling process and pay the price in November, botching health reform at the eleventh hour is a must.

Obama, speaking last Wednesday about the path to passage, declared, "I do not know how this plays politically, but I know it's right." Well, here's how it plays politically, especially for those timorous congressional Democrats who think that waving the white flag might be the best way to save their skins in November:

The Republicans will hammer them anyway, either for voting Yes the first time around (when health reform passed both chambers late last year), or for simply being members of the party that passed it the first time around. And if they vote No the second time around this spring, thereby scuttling reform altogether, the Democratic base will hammer them as gutless wonders and simply stay home.

That's the worst Democratic scenario. The best one, admittedly less than ideal, is to get the thing done, reap the upside in a White House signing ceremony, and start selling the benefits to the millions of skeptics who have been overly focused on the downside (thanks in part to the opposition messaging, and the ceaseless news coverage of the endless legislative gridlock). In politics, it's always preferable to be on the march, playing offense. It's tough to persuade the voters about anything if you're in retreat.

Obama, in his Saturday radio address, tried to spell out the upside: "While it will take a few years to fully implement these reforms, there are numerous protections and benefits that would start to take effect this year. This year, small-business owners will receive tax credits to purchase health insurance. This year, thousands of uninsured Americans with preexisting conditions will finally be able to purchase coverage. Insurance companies will no longer be allowed to deny coverage to children with preexisting conditions. And they will no longer be allowed to drop your coverage when you get sick."

In fact, the persuasion effort might not be as daunting as generally assumed. A number of surveys - notably, the latest Kaiser Family Foundation tracking poll - show majority support for key reform provisions. Kaiser says that seven in 10 Americans believe that the government should be (among other things) "reforming the way health insurance works," "providing financial help for lower and middle income people," and "creating a health insurance exchange."

Kaiser also says that 58 percent would be "disappointed" or "angry" if the Democratic Congress drops the ball on health reform. Granted, the polls show less support for the specific health reform bills that have long been twisting in the wind, but the critics include liberals who don't think the bills go far enough, and others who are upset with the endless congressional dithering. At minimum, the Kaiser statistics suggest that Obama and the Democrats would have something to work with, post-passage. The latest McClatchy/Ipsos poll, conducted by Ipsos Public Affairs, underscores the sales potential; in the survey, grassroots Democrats favor the reform effort, 62 to 24 percent; and independents favor it as well, 43 to 41 percent.

Obama said last Wednesday, "At stake right now is not just our ability to solve this problem, but our ability to solve any problem. The American people want to know if it's still possible for Washington to look out for their interests and their future." Basically, he was telling the Democrats that if they don't show some guts and get this done, they'll die in droves in November.

One final thought. Republicans keep warning that the Democrats would be nuts to enact health reform; that, by doing so, the Democrats would be committing political suicide; as ex-Bush pollster Matthew Dowd claimed on ABC the other day, the passage of health reform "is what we want to see happen, because of how unpopular this measure is."

But wait...If the Republicans really want health reform to happen, then why are they fighting so fiercely to defeat it? Because they know that, if health reform happens, the Democratic base is more likely to be energized for November. Because they know that their own prospects for a successful November are enhanced if the Democratic base is badly demoralized.

Which is precisely why the congressional Democrats, for the sake of their own political interests, need to get this deal done. The base won't turn out for a bunch of losers.